Diaphragm actuated pressure regulators generally operate by placing a flexible diaphragm in fluid communication with an area the pressure of which is maintained to be equivalent to the fluid line pressure being regulated. As the pressure in this area fluctuates, the diaphragm deflects proportionally. There is typically provided a counteracting spring force to regulate the diaphragm so that it deflects in a predictable fashion. It is known to control the movement of a valve which regulates the flow of fluid into the fluid line, and consequently into the area abutting the diaphragm, by means of a mechanical linkage connecting the valve to the diaphragm so that the deflection of the diaphragm has a direct impact on the rate of that fluid flow into the area and fluid line thus regulating the fluid pressure.
If the overall size of the regulator were otherwise inconsequential, it would be advantageous to employ as large a diaphragm as possible. This is because a large diaphragm, in conjunction with a small lever ratio, provides the necessary power to position the valve. The small lever ratio reduces the required deflection stroke which enables the regulator to operate with a higher degree of precision than a regulator having a smaller diaphragm with a longer stroke.
Two operating problems arise when a conventional diaphragm having a long stroke is used. The diaphragm area changes and the spring force changes over the range of the diaphragms' deflection stroke. Both of these factors are detrimental to the pressure control of the fluid passing through the regulator.
Another advantage to having a large diaphragm is that less pressure needs to be exerted on the diaphragm to generate a sufficient force on the linkage and valve to lock up the regulator so that all fluid flow to the fluid line is stopped. A typical regulator of this type will have a diaphragm of 26 square inches and a lever ratio of 3:1. Accordingly, when 1 psi. of outlet pressure is exerted on this diaphragm a resulting lock-up force of 78 pounds is generated to close off the valve.
Accordingly, known diaphragm actuated pressure regulators often use a diaphragm which is large enough so that with a typical lever ratio they will afford the desired pressure control. Regulators using these large diaphragms, however, are relatively expensive to manufacture and obtrusive when installed.
Due to the nature of the environments in which pressure actuators of this type are used, it is desirable that they be of as compact construction as possible. This is also desirable for the purpose of reducing material costs. It is generally not advisable, therefore, to use large diaphragms.
Known diaphragm actuated pressure regulators have been able to reduce the size of the diaphragm used by providing diaphragms with changeable surface areas and complicated linkages. By so doing, known regulators have been able to provide a longer deflection stroke with less material deformation than conventional pressure regulators having smaller diaphragms with longer strokes. One such regulator is described in U.S. Pat. No. 2,651,328 to C. B. Gamble.
These known pressure regulators, however, can be complicated to manufacture and operate. In an effort to translate the vertical deflection of the diaphragm to an increased horizontal displacement of the valve, known regulators such as the cited patent have used linear multi-part linkage assemblies. These linkages are difficult to assemble during construction of the regulator and the linkage joints can become loose and impair the precision of the device.
It is therefore an object of the present invention to provide a diaphragm actuated pressure regulator that uses a relatively small diaphragm which can be operated with a long stroke without experiencing material deformation and therefore a lack of precision.
It is another object of the present invention to provide a diaphragm actuated pressure regulator with a relatively small diaphragm and a relatively large lever ratio.
It is yet another object of the present invention to provide a diaphragm actuated pressure regulator that has a more compact construction than known pressure regulators offering the same amount of lock up force.
It is still another object of the present invention to provide a diaphragm actuated pressure regulator that has a simpler construction than known pressure regulators.